Amplifier switch

ABSTRACT

The invention relates to an improved amplifier switch which for example has the following features: between an in-gate ( 1; 1.1, 1.2 ) and an out-gate ( 3; 3.1, 3.21 ) an amplifier branch ( 5; 5.1. 5.1 ) and at least one bridging line ( 7; 7.1, 7.2 ) that can be switched on and off in parallel thereto are provided. At the outlet side, an amplifier branch ( 5; 5.1, 5.2 ) is connected to a pertaining bridging line ( 7; 7.1, 7.2 ) via summing circuit or a summing point ( 17 ) that is/are linked with the out-gate ( 3; 3.1, 3.2 ) The bridging line ( 7; 7.1, 7.2 ), between the pertaining switch contact (K 1 ) of the pertaining switch ( 9; 9.1, 9.2 ) and the summing circuit or the summing point ( 17 ), has an electrical length that corresponds to λ/2.

The invention relates to an amplifier switch as claimed in the preamble of claim 1.

It is known to use redundant circuits, in particular in radio frequency amplifier equipment.

Such a redundant circuit arrangement according to the genus-forming prior art, such as is known basically from U.S. Pat. No. 5,418,490, comprises an amplifier circuit which is provided between an input gate and an output gate. This amplifier circuit has two amplifier stages which are connected in parallel, both stages being capable of being switched on and off at the input end and the output end by using a switch, generally a relay switch. One of the two amplifier stages is connected through via the input-end and output-end relay, whereas the input and output of the second amplifier stage which is arranged in parallel is switched off. If the amplifier stage which is switched on fails, the contacts of the input-end and output-end relays are switched over to the second amplifier which was previously not required. If the second amplifier stage should also fail, in each case one relay switch is also connected in series with the input-end and output-end switchover relays in order to switch over between the two amplifier stages so that in such a case a through-connection path which is parallel with the two amplifier stages is connected through while bypassing both amplifiers.

Embodiments in which both parallel amplifier stages are connected together continuously in a parallel mode are basically also known. If one amplifier stage fails, at least the second amplifier stage remains active.

However, a failure in an amplifier stage leads to a reduction in amplification (for example of 4 to 8 dB) and to an increase in the noise coefficient by, for example 2 to 4 dB. In addition, there is no optimum adaptation to the input and output. This operating state must therefore be referred to as a worsened operating condition which makes repair absolutely necessary. A further problem with this embodiment is that, for example, in the case of an electrical discharge (lightning strike, etc.) both amplifier stages may also fail in this case, as both amplifier stages are basically operating in parallel.

The object of the present invention is to provide an amplifier switch which is improved in comparison with the above, in particular for a circuit having at least two amplifier circuits or amplifier stages, in which case the amplifier switch is to have in particular a low throughput attenuation in the bypass mode and a very good adaptation in the amplifier mode.

The object is achieved according to the invention in accordance with the features specified in claim 1 or 3. Advantageous refinements of the invention are given in the subclaims.

The invention uses surprisingly simple means to achieve significant improvements in comparison with the prior art.

The amplifier switch according to the invention can already be implemented with a single amplifier circuit or stage. Whereas, in the prior art, the switch, preferably in the form of a relay, has to be provided respectively both at the input end and at the output end for a switching over process so that, in the case of a defect, it is possible to switch over from the amplifier branch into a bridging path in parallel with the amplifier branch, according to the invention, only a single switch, i.e. generally a switch relay, is now arranged at the input or at the output. The bridging path which leads from a switching contact of the switch device to a summing point in the amplifier path is now dimensioned in such a way that the electrical length is approximately λ/2. In other words, the open relay contact is operated across the λ/2-long bridging line with high impedance, transformed to the opposite gate, i.e. in the open circuit mode.

According to one preferred embodiment as claimed in claim 2, a PIN diode is also connected in the amplifier line between the amplifier and the summing point. This is because, if the amplifier stage is not operational, a connection without a PIN diode could lead to increased loading in the bridging line and throughput line. The amplifier stage can be connected with high impedance to the line by means of the PIN diode.

According to the invention, only one switch relay (in comparison with at least two switches in the prior art) is therefore necessary.

However, the advantages according to the invention are apparent, especially in the design of a redundant circuit.

This is because, in one particularly preferred embodiment of the invention, such a redundant circuit is then constructed with at least two amplifiers or amplifier stages in such a way that they are not connected in parallel with one another as in the prior art but rather cascaded in series. There are also no decoupling problems in this context.

The circuit operates here in such a way that in each case only one amplifier circuit and amplifier stage is switched on in a home position, when the respective bridging line is switched on by switching over the switch or relay, the amplifier there is thus switched off. If the activated amplifier stage fails, the relay can switch over to the bridging path, the relay or the switch of the further amplifier stage interrupting the connection to the bridging line and switching over in order to activate the associated amplifier stage. As a result, the same electrical conditions are always precisely present so that no damping problems or adaptation problems or other problems occur.

Above all, such a redundant circuit with two amplifier stages requires only two switches which may be arranged either on the input side or output side in relation to the respective amplifier stage.

The invention is explained in more detail below with reference to exemplary embodiments, in which, in particular:

FIG. 1 shows a first schematic exemplary embodiment;

FIG. 2 shows an exemplary embodiment which is modified in comparison with FIG. 1;

FIG. 3 shows an exemplary embodiment of a redundant amplifier circuit with two amplifier stages in a first exemplary embodiment and

FIG. 4 shows an exemplary embodiment which is modified once more.

FIG. 1 shows a first exemplary embodiment of an amplifier switch according to the invention which is provided between an input gate 1 and an output gate 3.

The circuit device comprises two branches, namely an amplifier branch 5 and a bridging line 7 which is arranged in parallel thereto.

The switch 9, generally a relay switch 9, is connected to the input gate 1, it being possible to switch over from the switch contact K1 to the switch contact K2. If the switch is in the switched state S2, the input gate 1 is connected to the switch contact K2, as a result of which the amplifier circuit 15 which is connected in the amplifier branch 5 is switched on.

If the input-end switch 9 switches over into the switched state S1, the amplifier circuit 15 is switched off and the bridging line 7 is connected to the input gate 1 via the contact K1.

In the switched position S2 which is shown in FIG. 1, the fed-in power therefore passes from the input gate 1 to the amplifier 15, the amplifier input power being conducted to the output gate 3 via a low-impedance PIN diode 19 which is additionally provided in the amplifier branch between the amplifier circuit 15 and the summing point 17. The bridging line 7 which is explained above and which has a disconnected terminal K1 in this switched state is, however, dimensioned in such a way that it has an electrical length which corresponds to approximately λ/2. As a result, the open relay contact K1 is now transformed in high-impedance fashion to the output gate 3 via this λ/2-long line. The bridging line 7, together with the amplifier branch 5, is connected to a summing point 17.

The exemplary embodiment according to FIG. 2 differs from that according to FIG. 1 in that an input-end switch 9 is no longer provided but instead an output-end switch 19, otherwise the electrical length of the bridging circuit 15 also corresponds again to approximately λ/2. In this embodiment, the series PIN diode 19 is connected to the input of the amplifier 15, i.e. upstream of the amplifier 15. In this case also, the electrical length of the bridging line 7 shown in FIG. 2 corresponds (in the disconnected state) to approximately λ/2.

The first exemplary embodiment of a redundant amplifier switch, in which two amplifier switches are connected in series according to exemplary embodiment 1, will now be described with reference to FIG. 3.

In this exemplary embodiment, the output gate 3.1 of the first amplifier switching stage therefore simultaneously constitutes the input gate 1.2 of the second amplifier switching stage. An input-end switch 9.1 or 9.2 is assigned here to each amplifier switching stage.

In the home position, for example, the first input-end switch 9.1 is switched to the switched position S2 in which the power which is fed in from the input gate 1 is fed via the amplifier branch 5.1 of the downstream PIN diode 13 of the second amplifier stage 5.2 in which the switch 9.2 is in the switched stage S1, that is to say the amplified power coming from the first amplifier stage is passed on to the output gate 3.2 via the bridging line 7.2.

Failure of the first amplifier stage 15.1 leads to a situation in which the first relay switch 9.1 is switched over into the switched position S1, and as a result the amplifier circuit 15.1 is bridged by switching on the associated bridging line 7.1. At the same time, the switch 9.2 of the second amplifier stage 15.2 is switched over from the position S1 according to FIG. 3 into the position S2 so that the second amplifier stage 15.2 is now activated.

As the two amplifier stages are basically of the same design and have the same functionality (with respect to amplification, HF behavior, adaptation, etc.), the same electrical conditions occur as before the switching over process.

A repair is not absolutely necessary but rather should be performed only in a reasonable time period in order to ensure as far as possible that the second amplifier does not also fail.

This circuit arrangement also has the advantage that, for example, in the case of an electrical discharge (lightning strike) and destruction of the first amplifier stage 15.1 caused as a result thereof, the second amplifier stage 15.2 is basically protected as it is decoupled. As a result of the switching over between the two relay switches 9.1 and 9.2 it is therefore possible to activate the intact amplifier stage 15.2.

Only if, after the failure of the first amplifier stage, the second amplifier stage 15.2 was also to fail at a later time before a repair is carried out, would the second switching contact 9.2 then also switch over again in such a way that the bridging line 7.2 which is provided there is also activated so that the input gate 1.1 is connected to the output gate 3.2 via the two bridging lines 7.1 and 7.2 which are connected in series. 

1. A redundant amplifier switch comprising: at least two amplifier branches, the at least two amplifier branches are connected between an input gate and an output, a circuit arrangement having associated switches in such a way that it is possible to produce an electrical connection between the input gate and the output gate via one of the plurality of amplifier branches or via the bridging line, wherein: the amplifier branches are connected in series in such a way that in each case the output gate of one amplifier branch is electrically connected to the input gate of a subsequent amplifier branch, a bridging line which can be switched on and off is provided in parallel with each amplifier branch, between the associated input gate and the associated output gate of said amplifier branch, the circuit arrangement for switching the transmission from one amplifier branch to another amplifier branch or to the bridging line respectively connected in parallel therewith is constructed in such a way a) that a switch via which the input gate is connected either to the amplifier branch or the associated bridging line is provided between the input gate and the assigned amplifier branch and the associated bridging line, and the amplifier branch is connected at the output end to the associated bridging line via a summing circuit or a summing point which is connected to the associated output gate of the relevant amplifier branch, or b) that a switch via which the output gate is connected either to the amplifier branch or the associated bridging line is provided between the output gate and the assigned amplifier branch and the associated bridging line, and, in this case, the amplifier branch is connected at the input end to the associated bridging line via a summing circuit or a summing point which is connected to the associated input gate, and the respective bridging line has, between the associated switching contact of the associated switch and the respectively assigned summing circuit or the respectively assigned summing point, an electrical length which corresponds to approximately λ/2.
 2. The redundant amplifier switch as claimed in claim 1, wherein a PIN diode is connected between the respective amplifier circuit and a relevant amplifier branch and the respective assigned summing circuit or the assigned summing point.
 3. The redundant amplifier switch as claimed in claim 1, wherein the switches are formed from relay switches, preferably from relay switches with a low throughput attenuation. 